1. Technical Field
The present invention relates to a test apparatus for testing a device under test, and to a performance board used for the test apparatus. In particular, the present invention relates to a test apparatus and a performance board for testing a device under test by using a signal of a high frequency.
2. Related Art
A method for inputting a predetermined test signal to a device under test is known as a method for testing a device under test such as a semiconductor circuit. For example, a test to a device under test is performed by determining whether an output signal outputted from the device under test in response to a test signal matches a predetermined expected value pattern or not. Additionally, in accordance with the recent trend of increasing the speed of semiconductor circuits, it is required to perform a test by using a test signal of a higher frequency.
FIG. 7 shows a configuration of a conventional test apparatus 300. The test apparatus 300 includes a pattern generating circuit 310, a waveform shaper 320, and a driver 330. The pattern generating circuit 310 generates a data pattern of a test signal to be inputted to a device under test 200. The waveform shaper 320 shapes a test signal based on the data pattern generated by the pattern generating circuit 310. The driver 330 inputs the test signal shaped by the waveform shaper 320 to the device under test 200.
In this case, the maximum frequency of a test signal that can be generated by the test apparatus 300 is defined by the maximum operating frequency of the pattern generating circuit 310, the waveform shaper 320, and the driver 330. For example, the maximum frequency of a test signal will be 250 MHz when the maximum operating frequency of the pattern generating circuit 310 is 250 MHz and the maximum operating frequencies of the waveform shaper 320 and the driver 330 are both 1 GHz.
In such a case, an embodiment is known to connect a plurality of pattern generating circuits 310 to a waveform shaper 320 as shown in FIG. 7, as one method for generating a faster test signal. In this case, the plurality of pattern generating circuits 310 generate a data pattern to be inputted to the waveform shaper 320 by an interleave technique. For example, when each of the two pattern generating circuits 310 is operated at the maximum operating frequency of 250 MHz as shown in FIG. 7, it is possible to generate a test signal of 500 MHz.
Note that Japanese Patent Application Publication No. 2002-350508 is listed herein as a prior art document.
When a much faster test signal is generated in the conventional test apparatus 300, it is necessary to connect a greater number of pattern generating circuits 310 to a waveform shaper 320. However, it is not possible to connect the number of waveform shapers 320 that is more than the number of pins for transmitting a signal between the pattern generating circuits 310 and the waveform shaper 320, or than the number of input pins of the waveform shapers 320. This restricts the maximum frequency of a test signal.
In addition, even when a multitude of pattern generating circuits 310 are connected to a waveform shaper 320, it is not possible to generate a test signal faster than the maximum operating frequency of the waveform shaper 320 and the driver 330. This also restricts the maximum frequency of a test signal.